A controlled-release fertilizer, which is also referred to as slow-release fertilizer, can releases a fertilizer ingredient according to a growth of a plant in a designated time and so it is useful for labor-saving. At the present day, various controlled-release fertilizers are suggested and put to practical use, because of ripening of age employed in agriculture, decrease of the number of the employed and increase of side-job farmers.
Japanese Examined Patent Publication No. Sho-54-39298-B describes a controlled-release granular fertilizer, which is coated with an inner layer of wax and outer layer of urethane resin.
However, for obtaining long-term, for example 100–200 days, effective controlled-release fertilizers, plenty of coating materials are needed according to JP Sho-54-39298-B.
The present invention provides a granular coated fertilizer, which can release fertilizer ingredients for a long time, by a smaller amount of coating materials than known coated fertilizers.